This application is based upon and claims priority to German Patent Application 100 25 720.8 filed May 25, 2000, which application is herein expressly incorporated by reference.
The present invention relates to a driving arrangement with a free-wheel coupling. The free-wheel coupling has a coupling sleeve and a coupling hub rotatably supported around a rotational axis in the coupling sleeve. During driving of the coupling hub in a rotational driving direction, a means causes a rotational slaving of the coupling sleeve in the rotational driving direction. The means enables a faster rotation of the coupling sleeve in the rotational driving direction than the coupling hub without rotational slaving.
Free-wheel couplings are known in very different constructional designs. In many driving systems, free-wheel couplings are used as overrunning clutches to protect the drive from lagging masses. According to the size of the rotating masses and the friction resistance of the system, different lag times are caused for the rotating elements. In agricultural machinery, it is important to limit the lag times of the rotating masses and the operational tools. Accordingly, this enables the operator to carry out work on the agricultural machinery such as removing foreign bodies. It is also known to provide separate electrical, hydraulical or mechanical breaks to reduce the lag times. This is cumbersome, and it requires high cost and separate control elements.
The invention provides a driving arrangement which offers an inexpensive solution to reduce lag times of the rotating masses and the operating tools.
A driving arrangement according to the invention, includes a free-wheel coupling with a coupling sleeve, and a coupling hub rotatably supported in the coupling sleeve around a rotational axis. A means causes a slaving of the coupling sleeve in the rotational driving direction when the coupling hub is driven in a rotational driving direction. This enables a faster rotation of the coupling sleeve in the rotational driving direction than the coupling hub without rotational slaving. The coupling sleeve has a first end face and a second end face. A Belleville spring is non-rotatably positioned relative to the coupling hub. The Belleville spring is pre-tensioned to frictionally abut, via a friction face, one of the end faces of the coupling sleeve.
In this driving arrangement it is advantageous that components of the free-wheel coupling can be used to reduce the lag times. Thus, a free-wheel coupling, which is used as an overrunning clutch, can also have, at the same time, a breaking function. Since both functions are combined into one component, the required installation space is minimized. This achieves a correspondingly compact design. Furthermore, the production costs are reduced since the components of the free-wheel coupling can also be used to take over the function as a break.
According to a second aspect of the present invention, the pretensioned Belleville springs are supported, via a friction face, against both end faces of the coupling sleeve. To increase the friction effect, the friction faces of the Belleville springs and/or the corresponding end faces of the coupling sleeve include means to increase the friction coefficient. Accordingly, a friction coating or a friction lining is used. A carbon paper is a proposed example of a friction lining. Friction coatings are advantageously arranged on the friction faces of the Belleville spring. The attachment is carried out below the annealing temperature of the material, from which the Belleville spring is manufactured. Therefore finished Belleville springs can be coated with a friction coating. In order to ensure that the Belleville spring is pre-tensioned and that a rotational fast connection to the coupling hub is achieved, each Belleville spring is connected to the coupling hub via projections or pins on the coupling hub. The projections or pins extend parallel to the rotational axis and recesses. The recesses are arranged on the Belleville spring to engage the projections or pins.
The pins are displaceably received in the bores of the coupling hub. Thus, the axial displacement of the smaller diameter of the Belleville spring for pre-tensioning during mounting is without effect on the connection with the coupling hub. Further, the pre-tensioning of the Belleville spring is adjustably designed so that adjustment can be carried out at a later stage.
Advantageously, the free-wheel coupling includes locking pawls as the rotational slaving between the coupling sleeve and the coupling hub. Such free-wheel couplings are simple in design and ensure a secure switching on or changing over to the torque transmission position. At the same time, it is advantageous that the Belleville springs ensure a softer switching on characteristic of the free-wheel coupling. This is improved due to the frictional arrangement.
In a further aspect of the invention, the coupling sleeve supports a gear. The coupling hub is connected to a shaft. Both form components of a gear box. Therefore, the friction lining or friction face can be carried out for a wet operation. The friction heat produced during the slowing down of the lagging masses can easily be transmitted away, via oil provided in the gear box housing.
From the following detailed description, taken in conjunction with the drawings and subjoined claims, other objects and advantages of the present invention will become apparent to those skilled in the art.